Injection molded articles of polypropylene resin compositions find application in various fields including automobile parts and household appliance parts because of their excellent mechanical properties, moldability and economic efficiency.
Materials used in the field of automobile parts include polypropylene; polypropylene-based materials that have improved impact resistance by the addition of rubber components such as ethylene-propylene copolymer (EPR), ethylene-butene copolymer (EBR), ethylene-octene copolymer (EOR), styrene-butadiene copolymer (SBR) and polystyrene-ethylene/butene-polystyrene triblock copolymer (SEBS) (Patent Documents 1 and 2); polypropylene materials that have improved rigidity by the addition of inorganic fillers such as talc, mica and glass fibers; and blend polymers that have high mechanical properties by the addition of rubber components and inorganic fillers. Studies are well underway to remedy flow marks (circular ripples) and weld marks, and consequently the proportion of polypropylene in the automobile parts has increased.
On the other hand, polypropylene molded articles are generally poor in scratch resistance and have a glossy appearance. Thus, they are frequently subjected to post treatments such as painting or skin application to improve design properties, and the excellent economic efficiency of the molded articles is not fully enjoyed. Advances in technology to remedy flow marks and weld marks have partially realized the elimination of post treatments for automobile interior parts. However, the low scratch resistance and high gloss have hindered the elimination of post treatments for parts that require particularly high design properties such as interior panels and console boxes.                [Patent Document 1] JP-A-2006-307015        [Patent Document 2] JP-A-2006-316103        